RU2319173C1 - Multi-functional radiolocation station for aircrafts - Google Patents

Abstract

FIELD: radiolocation.

SUBSTANCE: multi-functional radiolocation station for aircrafts consists of slit antenna, circulator, receiving-transmitting block, which includes receiving device, which in turn consists of UHF receiver and analog-digital processor of signals, which includes amplifier of intermediate frequency and analog-digital converter, transmitting device, which consists of power amplifier and modulator, and also set-point generator, synthesizer of frequencies and synchronizer, digital signal processor, digital data processor, elevation angle sensor and indicator, where digital processor of signals contains device for narrowing total directional diagram, consisting of commutator, first memory device, second memory device, difference device, first multiplication device and second multiplication device, slit antenna is made with structure having total and differential directional diagrams in elevation plane, and also receipt commutator is introduced, while in digital signal processor narrowing of total directional diagram for receipt is performed by means of differential directional diagram, and in digital data processor on basis of information about distance and elevation angle, height of obstacles is determined relatively to supporting plane (safety plane).

EFFECT: detection and determining of height of ground-based obstacles.

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Description

The invention relates to the field of radar and can be used on airplanes and helicopters.

Multifunctional airborne radar stations (BRLS) are known, which are installed on long-range planes of all classes to detect thunderheads and cumulus clouds, to survey the earth's surface in the front hemisphere, to detect ground structures and to determine the coastline of large reservoirs.

Analogs of such radars can be domestic radar radios "Gradient" and "Kontur", installed on aircraft such as "Yak" and "TU".

As a prototype considered multifunctional radar station A 813 "Contour".

The Kontur radar station is intended for installation on light airplanes of local air lines and heavy GA helicopters.

The Kontur radar was developed according to the traditional scheme with a magnetron transmitter; its description is given in the book Aircraft Radar Systems. - M.: Transport, 1988, p. 209.

The block diagram of the radar prototype is shown in figure 1

Radar contains:

1 - antenna unit, including;

- slot antenna - 2

- antenna drive - 3

4 - transceiver unit, including:

- transmitter - 5

- antenna switch - 6

- receiver - 7

8 - indicator unit, including:

- master oscillator - 9

- synchronizer - 10

- indicator - 11

- signal converter - 12

- storage memory device - 13

14 - front panel, the main element of which is:

- control panel - 15.

Multifunctional radar in modes of detecting lightning fronts, viewing the earth's surface, determining the coastline works as follows.

The synchronization of all units and devices is carried out by a synchronizer (10). The repetition frequency and duration of pulses generated by the synchronizer are determined by the frequency of the master oscillator 9, equal to 3 MHz. This frequency is the reference, from which all starting pulses are formed, including the transmitter start pulse (5). A powerful microwave pulse of the transmitter (5) (magnetron) through the antenna switch (6) enters the slot antenna (2) and is radiated into space. An overview of the space is carried out by the radiation pattern formed by the slot antenna (2) of the antenna unit (1). The slot antenna drive (3) moves the antenna along the azimuth and tilt angles.

The reflected signals received by the antenna (2) through the antenna switch (6) enter the receiver (7), where the microwave signal is converted into pulses of the intermediate frequency in the mixer. The signal then goes to the intermediate frequency pre-amplifier and then to the linear-logarithmic intermediate-frequency amplifier with a detector. From the output of the receiver (7), the video signals enter the indicator unit (8) to the signal converter (12), where they are converted from an analog form into a binary-quantized code in three quantization levels. From the signal converter (12), the signals enter the storage memory device (13), where five realizations of the signal are accumulated and stored. From the memory device, the signal enters the synchronizer (10) to the video amplifier, from which it enters the image brightness modulator on the screen of the CRT indicator (11).

The inclusion of the radar and control modes is carried out by bodies on the control panel 15.

The disadvantage of this multifunctional radar is the lack of the function necessary for flying the carrier at low altitudes — the detection and determination of the height of ground obstacles. As developments have shown, the implementation of the function of detecting and determining the height of ground obstacles requires the use of a narrow beam in the elevation plane to provide the necessary high accuracy of height measurement. However, in the above prototype of a multifunctional radar with a slit antenna aperture implemented, the angle of the radiation pattern in the elevation plane is θβ≥8 °. Such a wide directivity pattern in the elevation plane does not allow the reflected signals from ground obstacles (elevations, buildings, power transmission towers, pipes, etc.) to be selected from the reflected signals of the earth's surface (terrain background) falling into the same range element, and It does not allow to estimate the height of obstacles with the necessary accuracy.

The objective of the invention is the implementation of a multifunctional radar with an additional function - the detection and determination of the height of ground obstacles. In the proposed multifunctional radar, this function is provided by narrowing the antenna beam in the elevation plane to the reception, which eliminates the influence of reflection signals from the earth's surface and other reflectors coming at angles different from the specified angles determined by the reference plane - the safety plane.

The narrowing of the overall radiation pattern of the radar slotted antenna to the reception makes it possible to detect and estimate the height of ground obstacles with a given accuracy. This problem is solved in that a multifunctional radar uses a slot antenna with an electromechanical drive, in which, by the known methods, dividing the mirror area into two halves and applying waveguide bridges, a difference diagram in the elevation plane is formed in addition to the main beam (the total diagram of two halves of the antenna area).

To implement the task of narrowing the total diagram to the reception using a difference diagram in the digital signal processor, a device for narrowing the total beam is introduced.

The summation diagram is narrowed in a digital signal processor by subtracting from the same range signals received by the summary diagram, signals received by the difference diagram.

The signals of the difference diagram are subtracted with a certain weight, which determines the magnitude of the beam beam.

When the radar is operating during scanning of the antenna in the elevation plane, the received signals of the sum and difference channels after their initial processing are accumulated in the memory of the signal processor in range. During the secondary processing of the signals stored in the memory of the firing device, the signals of the difference channel And _Δ (difference diagram of the antenna) are subtracted from the same signals And _Σ along the distance of the total channel (total antenna diagram) according to the formula:

| And _Σ | -K | And Δ | = | And _Σ | _about

where K is the gain of the difference channel signals.

The magnitude of the narrowed angle θ _{β of the} total diagram for such a narrowing is determined by the gain "K" of the signals received by the difference diagram.

The value of the coefficient "K" is taken by a compromise between the value of the narrowed angle and the allowable power loss of the applied signal.

Additional narrowing of the total diagram and a decrease in the level of the side lobes of the radiation pattern is provided by multiplying the signals of the primary total diagram by the signals of the narrowed total diagram.

| And _Σ | · | And _Σob | = | And * _Σob |

As a result of such operations, when scanning the antenna along the elevation angle, signals of reflections from obstacles are formed in the coordinates range-height and are displayed on the indicator. To do this, in a digital data processor, information on distance and elevation information determines the height of obstacles relative to the reference height.

Figure 1 shows a block diagram of an on-board radar station of the prototype.

Figure 2 presents a block diagram of the proposed multifunctional radar.

Figure 3 presents a detailed structural diagram of a digital signal processor 11.

The proposed multifunctional radar station includes:

1 - slot antenna;

2 - transmitting device;

3 - circulator;

4 - reception switch;

5 - receiving device;

6 - analog-to-digital processor;

7 - power amplifier;

8 - modulator;

9 - frequency synthesizer-synchronizer;

10 - master oscillator;

11 - digital signal processor;

12 - digital data processor;

13 - indicator;

14 - microwave receiver;

15 - intermediate frequency amplifier;

16 - ADC;

17 - angle sensor;

18 is a transceiver unit including devices 5, 6, 7, 8, 9, 10, 11, 12, 14, 15 and 16.

20 is a device for fencing;

21 - switch;

22 - the first memory device;

23 - a second memory device;

24 - difference device;

25 is a first multiplication device;

26 is a second multiplication device.

The proposed multifunctional radar with the reduced composition of the equipment provides a solution to the listed tasks of the prototype, and also solves the additional problem of detecting and determining the height of ground obstacles during low-altitude flight.

It should be noted that the construction of radar equipment is currently significantly different in level from the construction of equipment for the period of the creation of the prototype radar.

First of all, this relates to the implementation of methods and equipment for digital signal processing, calculation of parameters and control signals using digital processors. In this regard, the digital signal processor 11 and the digital data processor 12 used in the proposed multifunctional radar are not distinguishing features (although they are not in the prototype radar) and in the claims they are included in the restrictive part.

The following is a description of the interaction and relationships of blocks and devices working in solving the problem of detecting and determining the height of ground obstacles.

To transmit radiating pulses to the slot antenna, the input-output of the antenna 1 through the circulator 3 is connected to the output of the transmitting device 2.

To receive the signals of the overall radiation pattern of the slot antenna 1, the input-output of the slot antenna 1 through the circulator 3 is connected to the first input of the receiving switch 4, the output of which is connected to the input of the receiving device 5. To receive the signals of the difference radiation pattern, the second output of the slot antenna is connected to the second input of the switch 4. For receiving switching signals received third input receiving switch 4 for switching signal F _k is connected to the third output of the data processor 12. In order to trigger the formation and synchronizes guides the signal output of the master oscillator 10 is connected to the first input of frequency synthesizer, the synchronizer 9. To run the transmission device first frequency synthesizer output-signal 9 to the synchronizer run F _n connected to the first input of the transmission device 2, and for the formation of the emitted microwave signal f, the second the output of the frequency synchronizer synthesizer 9 is connected to the second input of the transmitting device 2. To form an intermediate frequency of the received signal f _{pr the} third output of the frequency synchronizer synthesizer 9 by the heterode signal of a different frequency f _{c is} connected to the second input of the receiving device 5. To generate sampling signals of an analog-to-digital converter (ADC) 6, the fourth output of the frequency synchronizer synthesizer 9 is connected to the third input of the receiving device 5 by the frequency signal f _ca , and for synchronizing the operation of the digital processor 11, the fifth output signal of the synthesizer clock signal f _cn connected to the second input of the digital signal processor 11. In order to synchronize the digital data processor 12, the sixth output frequency-synthesizer synchro 9 izatora signal f _pD connected to the first input of the digital data processor 12. To control the modes of the synthesizer frequency synchronizer-9 first output digital data processor 12 is connected to the second input of frequency synthesizer, the synchronizer 9. Switching signals at the digital signal processor 11, in the mode of fusion of the total radiation pattern, the third output of the digital data processor 12 is connected to the fourth input of the digital signal processor 11 by the signal F _k . To control the operating modes and output the initial parameters the output of the digital data processor 12 is connected to the third input of the digital signal processor 11 (via a special interface in accordance with GOST).

To receive and process radar information, the first input of the signal processor 11 is connected via a special interface to the output of the receiving device 5, and to display the radar information, the first output of the digital signal processor 11 is connected to the first input of the indicator 13.

To narrow the overall radiation pattern to receive a signal in the digital signal processor 11, a liquefaction device 20 is introduced, consisting of a switch 21, a first memory device 22, a second memory device 23, a difference device 24, a first multiplication device 25, and a second multiplication device 26. Signal accumulation in the first 22 or second 23 memory devices are produced through a switch 21, to the input of which signals from the analog-to-digital signal processor 6 of the receiving device 5 are supplied.

The output of the receiving device 5 is connected to the input of the switch 21, the first output of the switch 21 is connected to the input of the first memory device 22. The second output of the switch 21 is connected to the input of the second memory device 23, the output of the first memory device 22 is connected to the first input of the difference device 24 and the second the input of the second multiplication device 26, the output of the second memory device 23 is connected to the first multiplication device 25, the output of which is connected to the second input of the difference device 24, the output of which is connected to the first input of the second Multiplication device 26, to display the radar information, the output of the second multiplication device is connected to the first input of the indicator 13.

For switching the signals of the total and differential channels during accumulation, the third output of the digital data processor 12 is connected to the fourth input of the signal processor 11 by the signal F _k .

To determine the height of the obstacles H _{pr the} elevation sensor 17 of the slot antenna 1 by the signal "β" is connected to the third input of the digital data processor 12, and the second output of the digital signal processor 11 by the range signal "D" is connected to the second input of the digital data processor 12.

To display information about ground-based obstacles in the range-height coordinates, the second input of the indicator 13 is connected to the fourth output of the digital data processor 12 by the signal H _pr and the third input of the indicator 13 is connected to the second output of the digital signal processor 11.

Radar in the detection and height measurement of obstacles operates as follows.

In the scanning mode of the antenna in the elevation plane, the power amplifier 7 of the transmitting device 2 amplifies the high-frequency pulses "f" coming from the synthesizer of the frequency synchronizer 9, and passes them through the circulator 3 to the slot antenna 1. With a slot antenna, these pulses are emitted into space and propagate in the direction determined by the radiation pattern of the slot antenna. The stability of the carrier frequency "f" is determined by the master oscillator 10. At the input of the modulator 8 from the synthesizer of the frequency synchronizer 9, start pulses (F _p ) are received, which are formed by dividing the frequency of the signal "f _g " of the master oscillator 10. The pulse duration is also formed in the frequency synthesizer -synchronizer 9 by using the period of the signal "f _g ".

A high-frequency carrier frequency signal f is also generated by a frequency-synthesizer synthesizer. From the master oscillator 10, a signal with a frequency f _g enters the frequency synthesizer-synchronizer 9, is multiplied to the frequency (f) and is used as the carrier frequency of the radar signal emitted by the slot antenna 1.

The modulator 8 modulates the high-frequency signal "f" by the generated pulses entering the power amplifier 7 of the transmitting device 2, having a given duration (τ), as well as a repetition period (T _p ), determined by a unique range. In order to reduce the mass and dimensions of the equipment, one receiving channel is used, while the reception of simultaneously incoming reflected signals received by the sum and difference diagrams is separated in time by the reception switch 4 so that the signal energy determined by the accumulation time was sufficient to detect obstacles with a given probability. This time is determined by the switching frequency Fk of the switch specified by the digital data processor 12. In the process of scanning the slot antenna 1, reflected signals from objects and the surface are received by the slot antenna 1, in which the signals received by the summary diagram through the circulator 3 and the switch 4 are received at the receiving device 5 . In the microwave receiver 14, these signals in the receiver mixer are mixed with the synthesizer signal of the frequency synchronizer f _c , resulting in the formation of intermediate frequency signals f _pr The signals of the intermediate frequency f _pr are fed to the analog-to-digital processor 6, where they are amplified in the intermediate-frequency amplifier of the IF amplifier 15 and fed to the analog-to-digital converter of the ADC 16 controlled by the clock signal f _ca , where they are converted to digital form. From the output of the ADC 16, the signals are supplied to the device 20 of the digital signal processor 11, synchronized by the signal f _SP .

Next, the signals of the summary diagram in the device unit 20 are fed to the switch 21. From the output of the switch 21, the signals are sent to the first memory device U _Σ 22.

The incoming reflected signals and received by the difference diagram of the slot antenna 1 directly from the slot antenna 1 are fed to the receiving switch 4, and then the signal of the difference diagram passes the same processing as the total signal. With this processing, the switches 4 and 21 (using the signal F _{k of the} digital processor 12) synchronously switch to sequential reception, processing and accumulation of signals in the memory devices 22 and 23 of the total and differential radiation patterns of the slot antenna 1. The summation of the total radiation pattern is made in digital signal processor 11 in the device 20 by narrowing of difference detector 24 and the first 25 and second multiplying devices 26 by subtracting the accumulated difference in each chart range cell signals U _Δ and signal components in the corresponding range of the total diagrams U _Σ. Before subtracting the signals, the signals of the difference diagram U _Δ are supplied from the second memory device 23 to the first multiplication device 25, where they are multiplied by the gain of the signals of the difference diagram "K". Then, the multiplied difference signal KU _Δ enters the difference device 24, where the signals from the total diagram U _Σ in the same range elements are received from the first memory device 22.

In the device of difference 24, the amplified signals of the difference diagram are subtracted from the signals of the same diagram with the same range | U _Σ | -K | U _Δ | = U _{Σ shrouds} . From the difference device 24, the signals are supplied to the second multiplication device 26, which also receives the signals of the total diagram from the first memory device 22. In the second multiplication device 26, the signals of the looped diagram are multiplied by the signals of the primary summary diagram U _{Σ shrouds} · U _Σ .

As a result of the multiplication, the chart is additionally narrowed, and the side lobes of the primary narrowed diagram are reduced.

The signals from the second multiplication device enter the indicator 13 at the moments of arrival of the signal reflected from ground obstacles, and are displayed in it in the coordinates of the range - height. For this, in the digital data processor 12, according to the information about the distance "D" coming from the digital signal processor 11 and the elevation angle "β" of the slot antenna 1 coming from the angle sensor 17, the obstacle height H _pr relative to the reference plane is determined.

N _CR = N _about -D · β,

where N _about - the height of the safe flight relative to the reference plane (safety plane);

D is the distance to the obstacle;

β is the elevation angle of the antenna relative to the horizontal plane passing through the axis of the carrier.

The measured value of the height of the obstacles N _CR also enters the indicator 13.

To display the radar information, the value of the range "D" in the indicator 13 comes from a digital signal processor 11.

The technical result consists in the possibility of detecting ground-based obstacles and determining their height in multifunctional radar stations, where according to the conditions for placing the antenna on aircraft, it is not possible to use an antenna with the aperture necessary to obtain a narrow beam.

The implementation of this invention allows the application of the gain of the signals of the difference diagram K = 5 to narrow the width of the total diagram to receive more than 10 times, which can significantly reduce the error in measuring the height of obstacles. In this case, the signal power loss will be no more than 2 dB.

Claims (1)

A multifunctional radar station for aircraft, consisting of a slot antenna, a circulator, a transmitter / receiver unit, including a receiver device, consisting of a microwave receiver and an analog-to-digital signal processor, including an intermediate frequency amplifier (IF) and an analog-to-digital converter (ADC), a transmitting device consisting of a power amplifier and a modulator, as well as a master oscillator, frequency synchronizer synthesizer, digital signal processor, digital processor yes data, as well as an elevation sensor and an indicator, while the input-output of the slot antenna through the circulator is connected to the output of the transmitting device, the output of the master oscillator is connected to the first input of the frequency synchronizer synthesizer, the first output of the frequency synchronizer synthesizer is connected to the first input of the transmitting device, and the second output of the frequency synchronizer synthesizer is connected to the second input of the transmitting device, the third output of the frequency synchronizer synthesizer is connected to the second input of the receiving device, the fourth output is the frequency synchronizer integrator is connected to the third input of the receiving device, and the fifth output is connected to the second input of the digital signal processor, the sixth output is connected to the first input of the digital data processor, the first output of which is connected to the second input of the frequency synchronizer synthesizer, and the second output is connected to the third the input of the digital signal processor, the first input of the digital signal processor is connected to the output of the receiver, and the first output of the digital signal processor is connected to the first input of the indicator , the output of the elevation sensor is connected to the third input of the digital data processor, and the second output of the digital signal processor is connected to the second input of the digital data processor, characterized in that the digital signal processor comprises an arcing device for summing the radiation pattern, consisting of a switch, a first memory device, and a second a memory device, a difference device, a first multiplication device and a second multiplication device, the slot antenna is structured with a sum and difference diagram for in the elevation plane, and a receive switch is introduced, the output of the circulator connected to the first input of the receive switch, the output of which is connected to the receiver, the output of the receiver is connected to the input of the switch, the first output of which is connected to the input of the first memory device, and the second output connected to the input of the second memory device, the output of the first memory device is connected to the first input of the difference device and the second input of the second multiplication device, the output of the second memory device is connected connected to the first multiplication device, the output of which is connected to the second input of the difference device, the output of the difference device is connected to the first input of the second multiplication device, the output of which is connected to the first input of the indicator, the third output of the digital data processor is connected to the third input of the reception switch and to the fourth input of the digital signal processor, the second indicator input is connected to the fourth output of the digital data processor, and the third indicator input is connected to the second output of the digital signal processor, when In the digital signal processor, the total radiation pattern is received using the difference radiation pattern, and in the digital data processor, the height of the obstacles relative to the reference plane (safety plane) is determined by the information on the range and elevation angle.

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